CN113985293A - Lithium ion battery expansion rate prediction method and device, electronic device and storage medium - Google Patents
Lithium ion battery expansion rate prediction method and device, electronic device and storage medium Download PDFInfo
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 73
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000012360 testing method Methods 0.000 claims abstract description 136
- 239000000178 monomer Substances 0.000 claims abstract description 48
- 238000007599 discharging Methods 0.000 claims abstract description 28
- 230000008859 change Effects 0.000 claims abstract description 24
- 239000000945 filler Substances 0.000 claims abstract description 23
- 230000006870 function Effects 0.000 claims description 35
- 238000004364 calculation method Methods 0.000 claims description 17
- 239000006260 foam Substances 0.000 claims description 12
- 238000012669 compression test Methods 0.000 claims description 11
- 238000013461 design Methods 0.000 claims description 7
- 238000004590 computer program Methods 0.000 claims description 6
- 238000006073 displacement reaction Methods 0.000 claims description 5
- 238000005457 optimization Methods 0.000 description 6
- 238000004422 calculation algorithm Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 241000894007 species Species 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- 241000197727 Euscorpius alpha Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000006399 behavior Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000010261 cell growth Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011478 gradient descent method Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/392—Determining battery ageing or deterioration, e.g. state of health
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The application relates to the technical field of batteries, and discloses a lithium ion battery expansion rate prediction method and device, electronic equipment and a storage medium, wherein the method comprises the steps of compressing each component of a battery in a charging and discharging state respectively to obtain a thickness change value of each component when the component is subjected to battery expansion force, wherein each component comprises a battery monomer and a filler; acquiring the rigidity of the test fixture, and acquiring the deformation of the fixture between two ends clamped by the test fixture when the expansion force is applied according to the rigidity of the test fixture; acquiring preset curves of the expansion force of the battery in different charging and discharging states according to preset relations among the thickness change value of each component, the deformation amount of the clamp and the expansion amount; obtaining a test curve of the expansion force borne by the battery monomer under the preset condition under different charge and discharge states; the expansion rate of the single battery can be accurately predicted according to the preset relation function, the preset curve and the test curve, which are established under different charging and discharging states and correspond to the expansion rate of the single battery.
Description
Technical Field
The present disclosure relates to the field of battery technologies, and in particular, to a method and an apparatus for predicting an expansion rate of a lithium ion battery, an electronic device, and a storage medium.
Background
The lithium ion battery monomer comprises components such as a positive plate, a negative plate, a diaphragm, electrolyte and the like, and in the charge-discharge cycle process, the thicknesses of the positive plate and the negative plate are increased to different degrees due to the continuous insertion and separation of lithium ions and the like, and the expansion behavior of the size of the lithium ion battery monomer in the thickness direction is macroscopically expressed. For the same lithium ion battery monomer, because of different design forms of the lithium ion battery module or the battery pack, the deformation resistance of the constraint parts on two sides of the lithium ion battery monomer is different, and in addition, the thickness and the rigidity of the fillers such as foam can also be different, so that the same lithium ion battery monomer is assembled in different modules or battery packs, and finally, the expansion force and the expansion rate which are shown are obviously different, and the service life and the electrical property of the lithium ion battery monomer are finally influenced; if the expansion rate of the single lithium ion battery under the constraint condition of the module or the battery pack can be accurately predicted, the structural design of the module and the battery pack can be facilitated, the pretightening force of the single battery can be optimized, and the service life and the electrical property of the battery can be improved.
At present, the expansion rate of a lithium ion battery monomer is predicted in a manner that the lithium ion battery is directly fixed in a test fixture for charge and discharge cycle, and the deformation of the battery monomer in the charge and discharge cycle process is measured, so that the expansion rate of the lithium ion battery monomer is calculated.
Disclosure of Invention
The invention aims to provide a lithium ion battery expansion rate prediction method and device, electronic equipment and a storage medium.
In order to solve the above technical problem, a first aspect of the present application provides a method for predicting an expansion rate of a lithium ion battery, including: respectively carrying out compression test on each component of the lithium ion battery to be predicted in a test charge-discharge state, and calculating a thickness change value of each component when the component is subjected to battery expansion force, wherein each component at least comprises a battery monomer and a filler; acquiring the rigidity of a test fixture, and calculating the fixture deformation between two ends clamped by the test fixture when the test fixture is subjected to battery expansion force according to the rigidity of the test fixture; calculating preset relation curves of the battery expansion force in different test charging and discharging states according to the preset geometrical relation among the thickness change value of each component, the deformation of the clamp and the expansion generated by the battery expansion force; obtaining a test relation curve of the test expansion force borne by the battery monomer under the preset condition under different charge and discharge states; and acquiring the expansion rate prediction result of the single battery according to a preset relation function established by the expansion rate corresponding to the expansion amount of the single battery under different test charging and discharging states, the preset relation curve and the test relation curve.
In an embodiment of the first aspect, the obtaining a prediction result of the expansion rate of the single battery according to a preset relationship function, the preset relationship curve and the test relationship curve, where the preset relationship function is established in the different test charge-discharge states according to the expansion rate corresponding to the expansion amount of the single battery, specifically includes: calculating a standard difference value according to the preset relation curve and the test relation curve; and obtaining an expansion rate prediction result when the standard difference value is smaller than a reference threshold value according to a relation function established by the expansion rate corresponding to the expansion amount of the single battery under different test charging and discharging states.
In an embodiment of the first aspect, the obtaining, according to a relation function established by expansion rates corresponding to expansion amounts of the battery cells in different test charge/discharge states, an expansion rate prediction result when the standard deviation value is smaller than a reference threshold value includes: and establishing a relation function according to the expansion rate corresponding to the expansion amount of the single battery under different test charging and discharging states, reducing the standard difference value by taking the relation function as a design variable, and obtaining an expansion rate prediction result when the standard difference value is smaller than a reference threshold value.
In an embodiment of the first aspect, the reducing the standard deviation value by using the relation function as a design variable to obtain an expansion rate prediction result when the standard deviation value is smaller than a reference threshold includes: and carrying out iterative calculation on the relation function to obtain an expansion rate prediction result when the standard deviation value is smaller than a reference threshold value.
In an embodiment of the first aspect, the predetermined geometric relationship is Δ Hsystem＝△Hcell+△Hfoam+Hcellα, wherein Δ HsystemThe deformation of the fixture between the two ends of the test fixture is Delta HcellThe thickness change value, delta H, of the battery monomer under the expansion force of the batteryfoamIs the value of the change in thickness of the filler under the expansion force of the battery, HcellAnd alpha is the expansion rate of the battery monomer.
In an embodiment of the first aspect, the test charge-discharge state comprises the number of charge-discharge cycles N and the state of charge SOC of the battery cell.
In an embodiment of the first aspect, the preset conditions include that the battery cells are at the same temperature and humidity and at the same charge-discharge rate.
In an embodiment of the first aspect, the performing a compression test on each component of the lithium ion battery to be predicted in a test charge-discharge state, and calculating a thickness variation value of each component when the component is subjected to a battery expansion force respectively includes: respectively carrying out compression test on each component of the lithium ion battery to be predicted in a test charging and discharging state to obtain a pressure-displacement curve of each component, calculating a stress-strain curve of each component according to the pressure-displacement curve, and calculating a thickness change value of each component when the component is subjected to battery expansion force according to the stress-strain curve of each component.
In an embodiment of the first aspect, the obtaining rigidity of the test fixture and calculating a fixture deformation amount between two ends of the test fixture clamped by the test fixture when the test fixture receives an expansion force of the battery according to the rigidity of the test fixture includes: and calculating the rigidity of the test fixture by using a finite element method, acquiring a relation curve of the fixture deformation of the test fixture and the battery expansion force, and acquiring the fixture deformation according to the relation curve and the battery expansion force.
In an embodiment of the first aspect, the reference threshold is 5%.
A second aspect of the present application provides a device for predicting a swelling ratio of a lithium ion battery, including:
the first calculation module is used for calculating the thickness change value of each component when the component is subjected to battery expansion force when each component of the lithium ion battery to be predicted is subjected to compression test in a test charging and discharging state, wherein each component at least comprises a battery monomer and a filler;
the second calculation module is used for calculating the deformation of the clamp between the two ends clamped by the test clamp when the battery is subjected to expansion force according to the acquired rigidity of the test clamp;
the third calculation module is used for calculating a preset relation curve of the battery expansion force in different test charging and discharging states according to the preset geometrical relation among the thickness change value of each component, the deformation of the clamp and the expansion generated by the battery expansion force;
the first acquisition module is used for acquiring a test relation curve of the test expansion force borne by the battery monomer under a preset condition in different charging and discharging states; and
and the second obtaining module is used for obtaining the expansion rate prediction result of the single battery according to a preset relation function established by the expansion rate corresponding to the expansion amount of the single battery under different test charging and discharging states, the preset relation curve and the test relation curve.
A third aspect of the present application provides an electronic device comprising: at least one processor; and a memory communicatively coupled to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the lithium ion battery expansion rate prediction method described above.
A fourth aspect of the present application provides a computer-readable storage medium storing a computer program, wherein the computer program is executed by a processor to perform the above-mentioned lithium ion battery expansion ratio prediction method.
Compared with the prior art, the method can accurately predict the relation between the expansion rate of the battery and the charge-discharge cycle times and the state of charge.
Drawings
Fig. 1 is a schematic flow chart illustrating a specific method for predicting the expansion rate of a lithium ion battery according to a first embodiment of the present disclosure;
FIG. 2 is a schematic structural diagram illustrating a predetermined geometric relationship between deformation of members according to a first embodiment of the present disclosure;
fig. 3 is a schematic diagram of an electronic device according to a third embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application is provided by way of specific examples, and other advantages and effects of the present application will be readily apparent to those skilled in the art from the disclosure herein. The present application is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present application. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
Embodiments of the present application will be described in detail below with reference to the accompanying drawings so that those skilled in the art to which the present application pertains can easily carry out the present application. The present application may be embodied in many different forms and is not limited to the embodiments described herein.
In order to clearly explain the present application, components that are not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.
Throughout the specification, when a device is referred to as being "connected" to another device, this includes not only the case of being "directly connected" but also the case of being "indirectly connected" with another element interposed therebetween. In addition, when a device "includes" a certain component, unless otherwise stated, the device does not exclude other components, but may include other components.
When a device is said to be "on" another device, this may be directly on the other device, but may also be accompanied by other devices in between. When a device is said to be "directly on" another device, there are no other devices in between.
Although the terms first, second, etc. may be used herein to describe various elements in some instances, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, the first interface and the second interface, etc. are described. Also, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used in this specification, specify the presence of stated features, steps, operations, elements, components, items, species, and/or groups, but do not preclude the presence, or addition of one or more other features, steps, operations, elements, components, species, and/or groups thereof. The terms "or" and/or "as used herein are to be construed as inclusive or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a; b; c; a and B; a and C; b and C; A. b and C ". An exception to this definition will occur only when a combination of elements, functions, steps or operations are inherently mutually exclusive in some way.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" include plural forms as long as the words do not expressly indicate a contrary meaning. The term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and/or components.
Terms representing relative spatial terms such as "lower", "upper", and the like may be used to more readily describe one element's relationship to another element as illustrated in the figures. Such terms are intended to include not only the meanings indicated in the drawings, but also other meanings or operations of the device in use. For example, if the device in the figures is turned over, elements described as "below" other elements would then be oriented "above" the other elements. Thus, the exemplary terms "under" and "beneath" all include above and below. The device may be rotated 90 or other angles and the terminology representing relative space is also to be interpreted accordingly.
Although not defined differently, including technical and scientific terms used herein, all terms have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Terms defined in commonly used dictionaries are to be additionally interpreted as having meanings consistent with those of related art documents and the contents of the present prompts, and must not be excessively interpreted as having ideal or very formulaic meanings unless defined.
The expansion rate of the single lithium ion battery can be directly calculated in the conventional expansion rate prediction mode, but the following defects exist:
1) the effect of the stiffness of the test fixture on the cell expansion ratio is not fully considered.
The expansion rate of the single lithium ion battery is influenced by the pretightening force on the two sides of the single lithium ion battery, the rigidity and the constraint form of the test fixture are different, and the pretightening force on the two sides of the single lithium ion battery is also different, so that the expansion rate of the single lithium ion battery is influenced.
2) The influence of the compressive deformation of the lithium ion battery cell itself is not fully considered.
The thickness H ═ H macroscopically expressed by the lithium ion battery monomer0B is + Delta H-delta, wherein H0The initial thickness of the battery cell, the delta H is the thickness of the battery cell which is increased by the expansion deformation, and the delta is the deformation of the battery cell caused by the pre-tightening pressure on two sides.
3) The influence of the absorption deformation of a filler such as foam on the expansion rate of a battery cell is not sufficiently considered.
In a lithium ion battery module or a lithium ion battery pack structure, in order to absorb the expansion deformation of the battery cells, a filler such as foam is usually added between the battery cells or outside the battery cells. The position, rigidity and thickness of the filler can be different from those of the filler in the expansion rate test of the battery cell, so that the expansion rate prediction accuracy of the battery cell is influenced.
In view of the above-mentioned drawbacks, a first embodiment of the present application relates to a method for predicting an expansion rate of a lithium ion battery, where different test jigs are used to test the expansion rate and the expansion force of a lithium ion battery cell during charge and discharge cycles under the same conditions; calculating the rigidity of fillers such as different test fixtures, the rigidity of single batteries, foam and the like; using different fitting functions to represent the relation between the expansion rate and the Charge-discharge cycle number of the lithium ion battery monomer and the State of Charge (SOC) of the lithium ion battery monomer; calculating according to a stress balance equation and a material constitutive equation to obtain the expansion rate and the expansion force of the battery corresponding to different fitting functions, and comparing the calculated expansion rate and expansion force with a test result; and continuously optimizing and testing the obtained deviation between the expansion rate and the expansion rate through an optimization algorithm to obtain a proper relation between the expansion rate of the lithium ion battery unit and the charge-discharge cycle number N and the state of charge SOC, namely obtaining the expansion rate prediction result of the lithium ion battery. The expansion rate prediction method can accurately predict the expansion rate of the lithium ion battery monomer, the relation between the charge-discharge cycle number and the state of charge, the constraint condition of the lithium ion battery monomer in a module or a battery pack can predict the expansion rate and the expansion force in the whole period from the Beginning of the Life cycle (begin of Life, BOL) to the End of the Life cycle (End of Life, EOL) of a product, and further the service Life and the electrical property of the lithium ion battery can be improved through reasonable optimization of the structure of the module or the battery pack.
As shown in fig. 1, the method specifically includes the following steps:
step 101: and respectively carrying out compression test on each component of the lithium ion battery to be predicted in a test charge-discharge state, and calculating a thickness change value of each component when the component is subjected to battery expansion force, wherein each component at least comprises a battery monomer and a filler.
Specifically, each component of the lithium ion battery to be predicted comprises a battery monomer and a filler between a test fixture and the battery monomer, the battery monomer and the filler between the test fixture and the battery monomer are respectively subjected to compression test, pressure-displacement curves of the battery monomer and the filler under a compression condition are obtained, and stress-strain curves of the battery monomer and the filler are respectively obtained through calculation; assuming that a relation function alpha between a thickness direction expansion rate alpha and a number of charge-discharge cycles N and a state of charge SOC of a battery monomer due to continuous lithium ion intercalation and deintercalation and the like is f (N, SOC), the number of charge-discharge cycles N and the state of charge SOC are respectively set to be N under a test charge-discharge state0And SOC0The expansion force received by the battery cell in this determined state is F, and the expansion rate α in this determined state is F (N)0，SOC0). In general, the expansion ratio α in the thickness direction tends to increase with an increase in N and SOC, and the relation function α ═ f (N, SOC) may be set to a polynomial type, a power function, or the like, and is not limited here.
According to the stress-strain curve of the battery monomer, calculating the thickness change value delta H of the battery monomer when the battery monomer is subjected to the expansion force FcellAnd calculating the thickness change value delta H of the filler when the battery monomer is subjected to the expansion force F according to the stress-strain curve of the filler between the test fixture and the battery monomerfoam. However, it is understood that each member may include other members, and the thickness variation of the corresponding member may be calculated by acquiring the corresponding stress-strain curve of the member according to the embodiment of the present applicationAnd (4) converting the value.
Step 102: and acquiring the rigidity of the test fixture, and calculating the deformation of the fixture between the two ends clamped by the test fixture when the expansion force of the battery is applied to the test fixture according to the rigidity of the test fixture.
Specifically, different test fixtures are used for carrying out charge-discharge cycle tests on the battery cells under the same conditions (such as temperature and humidity and charge-discharge multiplying power), wherein the different test fixtures comprise different fixture materials, different fixture thicknesses and different fixture constraint forms, and the different fixture constraint forms comprise using bolts to constrain the relative distance between two ends clamped by the fixtures and using springs to constrain the relative pressure between the two ends clamped by the fixtures. And calculating the rigidity of different test fixtures in the charge-discharge cycle test by using a finite element method, and further acquiring a relation curve between the deformation and the expansion force of each test fixture. Assuming that the test fixture determines that the number of charge-discharge cycles and the state of charge are respectively N0And SOC0When the expansion force of the single battery is F, calculating the deformation quantity delta H of the clamp between two ends of the test clamp when the single battery is subjected to the expansion force F according to the relation curve u (F) (F) between the deformation quantity and the expansion force of the test clampsystem。
Step 103: and calculating a preset relation curve of the battery expansion force under different test charging and discharging states according to the preset geometrical relation among the thickness change value of each component, the deformation of the clamp and the expansion generated by the battery expansion force.
Specifically, as shown in FIG. 2, HsystemFor testing the distance between two ends of the clamp 01 (comprising an upper clamp 01a and a lower clamp 01b), HcellIs the initial thickness of the battery cell 02, HfoamFor the initial thickness of the filler 03, the deformation of each member should satisfy the following predetermined geometrical relationship:
△Hsystem＝△Hcell+△Hfoam+Hcell·α，
wherein Δ HsystemFor testing the deformation of the clamp between two ends of the clamp, Delta HcellThe thickness change value, delta H, of the battery monomer under the battery swelling force FfoamThickness variation of filler under expansion force of batteryValue of alpha is N0And SOC0Expansion rate of cell monomer in charge and discharge state, i.e. alpha ═ f (N)0，SOC0). Calculating and obtaining the expansion force F of the battery in N according to the preset geometric relation0And SOC0Expansion force F ═ F (N) in charge-discharge state0，SOC0). Changing the size of N and SOC to N respectivelyiAnd SOCiAnd performing iterative calculation for multiple times to obtain a preset relation curve F between the expansion force F and the charge-discharge cycle number N and the state of charge SOC, wherein F is equal to F (N, SOC). In the same way, different test fixtures are changed, and the preset relation curves between the expansion force F, the charge-discharge cycle number N and the state of charge SOC under different test fixture conditions can be obtained through the same calculation mode.
Step 104: and obtaining a test relation curve of the test expansion force of the battery monomer under the preset condition under different charge and discharge states.
Specifically, the battery cell is constrained in a test fixture, and a charge-discharge cycle test is performed under the same conditions (such as temperature, humidity and charge-discharge rate), so that the expansion force F tested in the charge-discharge cycle test is obtained when the battery cell reaches the Beginning (boil of Life) of the product Life cycle to the End (End of Life, EOL) of the product Life cycletestTest relation curve F along with charge-discharge cycle number N and state of charge SOC changestestG (N, SOC); in the same way, different test fixtures are changed, and the test expansion force F under different test fixture conditions can be obtained through the same test modetestAnd (4) a test relation curve between the number N of charge and discharge cycles and the state of charge SOC.
Step 105: and obtaining the expansion rate prediction result of the single battery according to a preset relation function, a preset relation curve and a test relation curve, wherein the preset relation function is established under different test charging and discharging states by the expansion amount corresponding to the expansion rate of the single battery.
Specifically, the test expansion force F obtained in step 104 is measuredtestTest relation curve F along with charge-discharge cycle number N and state of charge SOC changestestG (N, SOC) and the expansion force F and charge calculated in step 103And comparing a preset relation curve F between the discharge cycle number N and the state of charge SOC (the SOC) to obtain a standard difference value between the two curves. The method comprises the steps of carrying out iterative optimization by taking the relation function alpha-f (N, SOC) as a design variable according to the relation function alpha-f (N, SOC) established by the expansion rate corresponding to the expansion amount of a battery cell under different test charge-discharge states, wherein in the iterative optimization, the expression of the relation function alpha-f (N, SOC) is changed, such as changing the coefficient and the number of times of a polynomial, the base number of an exponential function and the like, an iterative algorithm can use a gradient descent method, a Newton method and the like, the iteration target is to reduce the standard difference value, and the expansion rate prediction result when the standard difference value is smaller than a reference threshold value is obtained, wherein the reference threshold value can be 5%, and at the moment, the corresponding relation function alpha-f (N, SOC) is the prediction result of the expansion rate of the lithium ion battery cell.
The lithium ion battery expansion rate prediction method can accurately predict the relation between the expansion rate of the lithium ion battery monomer and the charge-discharge cycle number and the charge state, and further can improve the service life and the electrical property of the lithium ion battery through reasonable optimization of a module or a battery pack structure.
The second embodiment of the application relates to a lithium ion battery expansion rate prediction device, which comprises a first calculation module, a second calculation module and a third calculation module, wherein the first calculation module is used for calculating the thickness change value of each component when the component receives the battery expansion force when each component of a lithium ion battery to be predicted is subjected to a compression test in a test charging and discharging state, and each component at least comprises a battery monomer and a filler;
the second calculation module is used for calculating the deformation of the clamp between the two ends of the test clamp when the test clamp is subjected to the expansion force of the battery according to the acquired rigidity of the test clamp;
the third calculation module is used for calculating a preset relation curve of the battery expansion force in different test charging and discharging states according to the thickness change value of each component, the deformation of the clamp and the preset geometrical relation of the expansion amount generated by the battery expansion force;
the first acquisition module is used for acquiring a test relation curve of the test expansion force borne by the battery monomer under the preset condition in different charging and discharging states;
and the second obtaining module is used for obtaining the expansion rate prediction result of the single battery according to the preset relation function, the preset relation curve and the test relation curve, which are established under different test charging and discharging states and correspond to the expansion rate of the single battery.
The embodiment definitely provides the expansion rate prediction device of the lithium ion battery, and the device can accurately predict the relation among the expansion rate of the lithium ion battery monomer, the charging and discharging cycle times and the charge state, so that the service life and the electrical property of the lithium ion battery can be improved through reasonable optimization of a module or a battery pack structure.
It should be understood that the present embodiment is a system embodiment corresponding to the first embodiment, and the present embodiment can be implemented in cooperation with the first embodiment. The related technical details mentioned in the first embodiment are still valid in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can also be applied to the first embodiment.
It should be noted that, all the modules involved in this embodiment are logic modules, and in practical application, one logic unit may be one physical unit, may also be a part of one physical unit, and may also be implemented by a combination of multiple physical units. In addition, in order to highlight the innovative part of the present invention, a unit which is not so closely related to solve the technical problem proposed by the present invention is not introduced in the present embodiment, but this does not indicate that there is no other unit in the present embodiment.
A third embodiment of the present invention relates to an electronic apparatus, as shown in fig. 3, including: at least one processor 401; and a memory 402 communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the above lithium ion battery expansion rate prediction method.
Where the memory and processor are connected by a bus, the bus may comprise any number of interconnected buses and bridges, the buses connecting together one or more of the various circuits of the processor and the memory. The bus may also connect various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. A bus interface provides an interface between the bus and the transceiver. The transceiver may be one element or a plurality of elements, such as a plurality of receivers and transmitters, providing a means for communicating with various other apparatus over a transmission medium. The data processed by the processor is transmitted over a wireless medium via an antenna, which further receives the data and transmits the data to the processor.
The processor is responsible for managing the bus and general processing and may also provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. And the memory may be used to store data used by the processor in performing operations.
A fifth embodiment of the present invention relates to a computer-readable storage medium storing a computer program. The computer program realizes the above-described method embodiments when executed by a processor.
That is, as can be understood by those skilled in the art, all or part of the steps in the method for implementing the embodiments described above may be implemented by a program instructing related hardware, where the program is stored in a storage medium and includes several instructions to enable a device (which may be a single chip, a chip, or the like) or a processor (processor) to execute all or part of the steps of the method described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.
Claims (12)
1. A lithium ion battery expansion rate prediction method is characterized by comprising the following steps:
respectively carrying out compression test on each component of the lithium ion battery to be predicted in a test charge-discharge state, and calculating a thickness change value of each component when the component is subjected to battery expansion force, wherein each component at least comprises a battery monomer and a filler;
acquiring the rigidity of a test fixture, and calculating the fixture deformation between two ends clamped by the test fixture when the test fixture is subjected to battery expansion force according to the rigidity of the test fixture;
calculating preset relation curves of the battery expansion force in different test charging and discharging states according to the preset geometrical relation among the thickness change value of each component, the deformation of the clamp and the expansion generated by the battery expansion force;
obtaining a test relation curve of the test expansion force borne by the battery monomer under the preset condition under different charge and discharge states; and
and acquiring the expansion rate prediction result of the single battery according to a preset relation function established by the expansion rate corresponding to the expansion amount of the single battery under different test charging and discharging states, the preset relation curve and the test relation curve.
2. The lithium ion battery expansion rate prediction method according to claim 1, wherein the obtaining of the expansion rate prediction result of the battery cell according to the preset relationship function, the preset relationship curve and the test relationship curve, which are established in the different test charge-discharge states according to the expansion rate corresponding to the expansion amount of the battery cell specifically includes:
calculating a standard difference value according to the preset relation curve and the test relation curve; and
and obtaining an expansion rate prediction result when the standard difference value is smaller than a reference threshold value according to a relation function established by the expansion rate corresponding to the expansion amount of the single battery under different test charging and discharging states.
3. The lithium ion battery expansion rate prediction method according to claim 2, wherein the obtaining of the expansion rate prediction result when the standard deviation value is smaller than a reference threshold value according to a relationship function established by expansion rates corresponding to expansion amounts of the battery cells in the different test charge-discharge states includes:
and establishing a relation function according to the expansion rate corresponding to the expansion amount of the single battery under different test charging and discharging states, reducing the standard difference value by taking the relation function as a design variable, and obtaining an expansion rate prediction result when the standard difference value is smaller than a reference threshold value.
4. The lithium ion battery expansion ratio prediction method according to claim 3, wherein the obtaining the expansion ratio prediction result when the standard deviation value is smaller than a reference threshold value by using the relation function as a design variable to reduce the standard deviation value comprises:
and carrying out iterative calculation on the relation function to obtain an expansion rate prediction result when the standard deviation value is smaller than a reference threshold value.
5. The lithium ion battery expansion ratio prediction method of claim 1, wherein the predetermined geometric relationship is Δ Hsystem＝△Hcell+△Hfoam+Hcellα, wherein Δ HsystemThe deformation of the fixture between the two ends of the test fixture is Delta HcellThe thickness change value, delta H, of the battery monomer under the expansion force of the batteryfoamIs the value of the change in thickness of the filler under the expansion force of the battery, HcellAnd alpha is the expansion rate of the battery monomer.
6. The lithium ion battery expansion ratio prediction method according to claim 1, characterized in that the test charge-discharge state comprises a charge-discharge cycle number N and a state of charge SOC of a battery cell.
7. The lithium ion battery expansion rate prediction method according to claim 1, wherein the preset conditions include that the battery cells are at the same temperature and humidity and at the same charge-discharge rate.
8. The lithium ion battery expansion rate prediction method according to claim 1, wherein the performing compression tests on the components of the lithium ion battery to be predicted respectively in a test charge-discharge state and calculating the thickness variation values of the components when the components are subjected to battery expansion force comprises:
respectively carrying out compression test on each component of the lithium ion battery to be predicted in a test charging and discharging state to obtain a pressure-displacement curve of each component, calculating a stress-strain curve of each component according to the pressure-displacement curve, and calculating a thickness change value of each component when the component is subjected to battery expansion force according to the stress-strain curve of each component.
9. The lithium ion battery expansion rate prediction method of claim 1, wherein the obtaining of the rigidity of the test fixture and the calculating of the fixture deformation between two ends of the test fixture clamped by the test fixture when the battery is subjected to the expansion force according to the rigidity of the test fixture comprises:
and calculating the rigidity of the test fixture by using a finite element method, acquiring a relation curve of the fixture deformation of the test fixture and the battery expansion force, and acquiring the fixture deformation according to the relation curve and the battery expansion force.
10. An expansion rate prediction device for a lithium ion battery, comprising:
the first calculation module is used for calculating the thickness change value of each component when the component is subjected to battery expansion force when each component of the lithium ion battery to be predicted is subjected to compression test in a test charging and discharging state, wherein each component at least comprises a battery monomer and a filler;
the second calculation module is used for calculating the deformation of the clamp between the two ends clamped by the test clamp when the battery is subjected to expansion force according to the acquired rigidity of the test clamp;
the third calculation module is used for calculating a preset relation curve of the battery expansion force in different test charging and discharging states according to the preset geometrical relation among the thickness change value of each component, the deformation of the clamp and the expansion generated by the battery expansion force;
the first acquisition module is used for acquiring a test relation curve of the test expansion force borne by the battery monomer under a preset condition in different charging and discharging states; and
and the second obtaining module is used for obtaining the expansion rate prediction result of the single battery according to a preset relation function established by the expansion rate corresponding to the expansion amount of the single battery under different test charging and discharging states, the preset relation curve and the test relation curve.
11. An electronic device, comprising:
at least one processor; and
a memory communicatively coupled to the at least one processor,
wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the lithium ion battery expansion ratio prediction method of any of claims 1-9.
12. A computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the lithium ion battery expansion ratio prediction method according to any one of claims 1 to 9.
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